Australia’s corporate watchdog has begun enquiries into the hoax which rocked local markets today and temporarily wiped more than $314 million off the value of Whitehaven Coal.

The Australian Securities and Investments Commission confirmed this afternoon that enquiries are underway and that could see the commission target anti-coal activist Jonathan Moylan for questioning over the stunt.

Quick to recover ... Whitehaven's share price returned to normal once the hoax was revealed.

"We will be speaking to the people involved," said ASIC in a statement.

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Mr Moylan sparked a sudden sell-off in Whitehaven shares around midday today when he released what appeared to be a press release from ANZ Bank.

ANZ arranged a $1.2 billion loan for Whitehaven in December to help the company build a new coal mine in New South Wales, but Mr Moylan's hoax email suggested that ANZ had gone back on its decision and would no longer lend the money.

The press release saw Whitehaven shares slump almost 9 per cent from $3.52 to $3.21 shortly after midday in a fall that wiped about $314 million off the value of the company.

Whitehaven was put into a trading halt but has resumed later in the afternoon, the stock recovered to be down 2 cents for the day at $3.50.

Mr Moylan has since admitted his role in the hoax and claimed it was justified by the environmental destruction he said would be wrought by the mine, near Narrabri in NSW.

"We considered the decision to run a spoof very carefully before we did it, but we believe it is justified,’’ Mr Moylan said. ‘‘We think it is a bit like the Chaser getting into APEC, or the Yes Men announcing that Union Carbide had shut down."

Asked if he had qualms about lying to the public to achieve environmental ends, he said: ‘‘Our primary concern is the impact of this mine on the environment at the end of the day. A lot of people were taken in by it, but when you compare the cost of that to the health of our forests and farmlands, it justifies it.’’

Asked if the anti-coal group had considered that Whitehaven might pursue legal action it, Mr Moylan said: ‘‘I’m not prepared to comment on that at this time.’’

Neither Whitehaven nor ANZ have given any indication over whether they will pursue legal action against Mr Moylan.

Whitehaven's biggest shareholder Nathan Tinkler has also declined to comment on whether he will launch legal action.

But ASIC has confirmed that it is looking into whether the hoax breached any of the rules that are governed by the commission.

"ASIC's initial enquires will focus on if there has been a breach of the Corporations Act (Section 1041E - false or misleading statements). If there appears to be a breach, ASIC will investigate and take timely and appropriate action,'' said an ASIC spokesman.

The hoax is the third time in six months that an ASX listed company has had its share price affected by hoaxes, after similar stunts affected retailer David Jones in July and MacMahon Holdings in October.